I know they are usually very cheesy, but whenever im on vacation I always pack a workout dvd. If it starts raining or im the first one up in the morning I just pop it in and in a half hour I got my workout out of the way for the day!!! Plus if you make the room to pack it on top you'll see it every time you pull something out of your suit case and it will remind you to stay on track!!
My personal faves are Jazzercise DVDs :)